Joe,
Here is my 2 cents on the subject. Crank up the adjuster and take it for a ride. If its not handling like you want crank it up some more, unless the handling issue is because it is to hard then back it off some. Trial and error works for me. I like to find a nice long turn that you can take at a comfortable speed. Set the bike into the turn and really relax your grip to the point of almost turning loose of the bars, no physical input. If you come out of the turn a bit wide crank in a little more preload. If it trys cutting the apex to soon then back a little preload out. With a topbox mounted I had to crank in a little more preload to keep the front tire planted above 80. You need to be comfortable with your setup.
I ran the stock Dunlop's at 42 like the manual says. When I switched to the Avon Azaro their suggested front pressure was 36 and that's what I run even now running the Storms. Tire pressure will again be based on bike load too. More load, more pressure until you have reached the max. limit.